ezmsg.simbiophys.system.velocity2lfp#

Convert polar velocity coordinates to simulated LFP-like colored noise.

This module provides a system that encodes velocity (in polar coordinates) into the spectral properties of colored (1/f^beta) noise, producing LFP-like signals.

Pipeline:
polar coords (magnitude, angle) -> cosine encoder (beta values) -> clip

-> colored noise -> mix to channels

The velocity is encoded using a cosine tuning model where multiple noise sources have different preferred directions. Each source’s spectral exponent (beta) is modulated by the velocity direction and magnitude. These sources are then mixed across output channels using a spatial mixing matrix.

Note

This system expects polar coordinates as input. Use CoordinateSpaces with mode=CART2POL upstream to convert Cartesian velocity (vx, vy) to polar coordinates (magnitude, angle).

See also

ezmsg.simbiophys.system.velocity2spike: Velocity to spike encoding. ezmsg.simbiophys.system.velocity2ecephys: Combined spike + LFP encoding.

Classes

class Velocity2LFP(*args, settings=None, **kwargs)[source]#

Bases: Collection

Encode velocity (polar coordinates) into LFP-like colored noise.

This system converts polar velocity coordinates into multi-channel LFP-like signals:

  1. Cosine encoder: Each of n_lfp_sources has a different preferred direction. The spectral exponent beta (0-2) is modulated by the cosine of the angle between velocity and preferred direction, scaled by speed.

  2. Clip: Ensures beta values stay within valid range [0, 2].

  3. Colored noise: Generates 1/f^beta noise where beta is dynamically modulated per source.

  4. Spatial mixing: Projects the n_lfp_sources onto output_ch channels using a sinusoidal mixing matrix with random perturbations.

Input:

AxisArray with shape (N, 2) containing polar velocity coordinates. Dimension 0 is time, dimension 1 is [magnitude, angle]. Use CoordinateSpaces(mode=CART2POL) upstream if starting from (vx, vy).

Output:

AxisArray with shape (M, output_ch) containing LFP-like colored noise at output_fs sampling rate.

Parameters:

settings (Settings | None)

SETTINGS#

alias of Velocity2LFPSettings

INPUT_SIGNAL = InputStream:unlocated[AxisArray]()#
BETA_ENCODER = <ezmsg.simbiophys.cosine_encoder.CosineEncoderUnit object>#
CLIP_BETA = <ezmsg.sigproc.math.clip.Clip object>#
PINK_NOISE = <ezmsg.simbiophys.dynamic_colored_noise.DynamicColoredNoiseUnit object>#
MIX_NOISE = <ezmsg.sigproc.affinetransform.AffineTransform object>#
OUTPUT_SIGNAL = OutputStream:unlocated[AxisArray](self.num_buffers=32, self.force_tcp=False)#
configure()[source]#

A lifecycle hook that runs when the Collection is instantiated.

This is the best place to call Unit.apply_settings() on each member Unit of the Collection. Override this method to perform collection-specific configuration of child components.

Return type:

None

network()[source]#

Override this method and have the definition return a NetworkDefinition which defines how InputStreams and OutputStreams from member Units will be connected.

The NetworkDefinition specifies the message routing between components by connecting output streams to input streams.

Returns:

Network definition specifying stream connections

Return type:

NetworkDefinition

class Velocity2LFPSettings(output_fs=30000.0, output_ch=256, n_lfp_sources=8, max_velocity=315.0, seed=6767)[source]#

Bases: Settings

Settings for Velocity2LFP.

Parameters:
output_fs: float = 30000.0#

Output sampling rate in Hz.

output_ch: int = 256#

Number of output channels (simulated electrodes).

n_lfp_sources: int = 8#

Number of cosine-encoded LFP sources. Each source has a different preferred direction and generates colored noise with velocity-modulated spectral exponent.

max_velocity: float = 315.0#
seed: int = 6767#

Random seed for reproducible preferred directions and mixing matrix.

__init__(output_fs=30000.0, output_ch=256, n_lfp_sources=8, max_velocity=315.0, seed=6767)#
Parameters:
Return type:

None